OS X 10.11.4 Intel Iris Pro - OpenCL Build Fails with GPU Rendering
No, AMD are not the only system GPGPUs that support Cycles OpenCL Rendering.

https://wiki.blender.org/index.php/OpenCL

But you are not alone. In OS X 10.11.4 with Iris Pro 6100 on the Macbook Pro 13" the kernel fails. The OpenCL support by Apple for the iGPU is OpenCL 1.2. It should work, but fails.

That onus is on Blender.